Borrowing it
Nothing to install: this file belongs to cardstack/boxel. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/cardstack/boxel/main/.claude/skills/key-shares/SKILL.mdgit clone --depth 1 https://github.com/cardstack/boxelWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/cardstack/boxel/key-shares)<a href="https://agentmods.dev/skills/cardstack/boxel/key-shares"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/key-shares/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/cardstack/boxel/key-shares"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/key-shares.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00210 | $0.02247 |
| Opus 5.5 | $0.00084 | $0.00899 |
| Sonnet 5.5 | $0.00042 | $0.00449 |
| Haiku 4.5 | $0.00021 | $0.00225 |
Grade A, and why
key-shares scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 148 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Key shares (operators)
A share puts a key into a realm so that other people there can consume it
(a weather subscription, say). It holds no secret, only a reference to the
key, so one key can be shared into several realms while its value is stored
once, in user_keys (see the user-keys skill). Using your own key in a
realm is a different thing and needs no share.
The code is packages/realm-server/lib/key-shares.ts (the rules) and
packages/realm-server/handlers/handle-key-shares.ts (the routes). The
triggers are in the migration that adds key_shares.
States and suspension reasons
A share is active or suspended. A suspended share serves nothing and
always carries one reason:
suspension_reason |
Made by | key_id |
Ends when |
|---|---|---|---|
owner-lost-write |
The owner's own permission row stops granting write, or is deleted (leaves) | kept | The owner's row grants write again (resumes by itself), or a direct writer swaps a key in |
suspended-by-writer |
A direct writer of the realm (suspended_by), for abuse or any reason |
kept | A direct writer resumes it, or swaps a key in |
key-deleted |
The owner deleted the key the share holds | null | A direct writer swaps a key in |
key_shares_state_check enforces these combinations. Only an active share is
suspended: a share suspended for one reason keeps that reason when another
applies too, so a share a writer suspended stays suspended when its owner
loses write and regains it. The exception is deleting the key: a share then
holds no key, so whatever it was suspended for, it becomes key-deleted
(clearing suspended_by), and the realm's writers get a notice of it. Resuming a suspended-by-writer share whose
owner is no longer a direct writer leaves it suspended as owner-lost-write,
and it resumes when they write again.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 5d ago First seen · 148 lines · 210 tokens per session scan A 3e7ecdbc6542
key-shares is a skill published in the GitHub repository cardstack/boxel (27 stars, last pushed today), licensed MIT. It adds 210 tokens to every session and 2,247 once invoked, about $0.0008 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-21.
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